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Doubled CO 2 precipitation changes for the Susquehanna Basin: down‐scaling from the Genesis general circulation model
Author(s) -
Crane Robert G.,
Hewitson Bruce C.
Publication year - 1998
Publication title -
international journal of climatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.58
H-Index - 166
eISSN - 1097-0088
pISSN - 0899-8418
DOI - 10.1002/(sici)1097-0088(199801)18:1<65::aid-joc222>3.0.co;2-9
Subject(s) - geopotential height , environmental science , precipitation , climatology , geopotential , humidity , atmospheric circulation , scaling , meteorology , atmospheric sciences , geology , geography , mathematics , geometry
Abstract Artificial neural nets are used in an empirical down‐scaling procedure to derive daily subgrid‐scale precipitation from general circulation model (GCM) geopotential height and specific humidity data. The neural net‐based transfer functions are developed using a 2°×2·5° gridded data assimilation product from the Goddard Space Flight Center, applied to a 4×4 matrix of grid‐cells centred on the Susquehanna river basin. The down‐scaled precipitation is a close match to the observed data (temporal correlations at individual grid‐points range from 0·6 to 0·84). Doubled CO 2 climate change scenarios are produced by applying the same transfer functions to the geopotential height and specific humidity fields from 1×CO 2 and 2×CO 2 simulations of version II of the GENESIS climate model. The analysis indicates a 32 per cent increase in spring and summer rainfall over the basin, resulting from changes in both moisture availability and the orientation of the storm track over the region. The down‐scaled precipitation increases, derived from the change in the GCM's circulation and humidity fields, are considerably larger than the change in the model's actual computed precipitation. © 1998 Royal Meteorological Society.